Social exclusion has been described as a form of social death because it is a major risk factor in many potentially life-threatening physical and mental health outcomes. Among adolescents, social exclusion is a major risk factor in peer victimization, depression and anxiety, engaging in harmful behaviors such as cigarette smoking, substance abuse, unprotected sex, and unhealthy eating (e.g., obesity), and school violence and other forms of aggression. Interventions to promote social integration often attempt to remediate individual deficits, such as developing friendship skills or improving social skills. Suc interventions are only moderately successful because they do not consider the power of indirect relationships to influence the health and well- being of socially excluded youth. Thus, there is an urgent need to investigate the effect of social network variables on outcomes for socially excluded youth. In this study, which is a collaboration between faculty from the Cincinnati Children's Hospital Medical Center, the University of Kentucky, and the College of William and Mary, data from over 1000 high school freshman and sophomores will be gathered twice each year, for two years. This large-scale, longitudinal study will address two important questions. First, what are the network variables that have the greatest influence on maladaptive outcomes for socially excluded youth? Second, what important environmental factors that moderate negative psychological and behavioral outcomes of socially excluded youth? Studies among adults examining constructs such as loneliness, well-being, and health- compromising behaviors experienced or displayed in one part of the network are spread via key individuals (liaisons, or brokers) located throughout the network. It is through these brokers that the full impact of the contagion spreads to distant parts of the network. Recent studies have explored the role of brokers in adolescent social networks, however these studies are based on cross-sectional data and have not explored the relationship between brokers and their relationship to excluded youth. It is hypothesized that socially excluded youth will demonstrate better outcomes to the extent that they have direct or indirect relationships with (a) socially competent individuals and (b) individuals who occupy brokerage roles in the social network. PUBLIC HEALTH RELEVANCE: The project is particularly relevant given the intra-/interindividual costs associated with factors strongly related to social exclusion. The findings o this study are expected to contribute important information on prevention and intervention strategies to improve the quality of life among excluded adolescents, in addition to fundamentally advancing the fields of adolescent development and social networks. Our study, which examines how these youth are affected by changes in distant part of the network where they have no ties, will advance the field in accordance with NIH's mission, which is to yield research that can help reduce costly health outcomes and enhance human health.